| Alpine Paving Limited | Administrative & support | 2014 |
| Alrogri Limited | Real estate | 2024 |
| Alsat Digital Services Limited | Professional & scientific | 2008 |
| Altacore Solutions Ltd. | Professional & scientific | 2010 |
| Alteh Ltd | Hospitality | 2025 |
| Altin Group Ltd | Construction | 2023 |
| Altosha Diagnostics Ltd | Administrative & support | 2015 |
| Alva Estates Limited | Financial services | 1961 |
| AMA Connections Ltd | Professional & scientific | 2016 |
| Amaila Travel & Tours T/A Silk Voyage Ltd | Administrative & support | 2024 |
| Amalika UK Ltd | Hospitality | 2022 |
| Amaranthus Ltd | Professional & scientific | 2025 |
| Amazing Eataly Limited | Hospitality | 2014 |
| Amazing Results! Ltd | Real estate | 2015 |
| AMBERREADS111 Limited | Arts & recreation | 2025 |
| AMC Management Consultancy Ltd | Professional & scientific | 2023 |
| Amcc Logistics Ltd | Transport & logistics | 2018 |
| Amco GAS Heating Limited | Administrative & support | 2016 |
| Amorist Ltd | Hospitality | 2021 |
| AMS Motor Services Ltd | Wholesale & retail | 2026 |
| Anannhall Ltd | Wholesale & retail | 2020 |
| Ancer Recruitment Ltd. | Administrative & support | 2000 |
| Anchor Consultants Limited | Administrative & support | 2007 |
| Anchor Nursing & Social Care Limited | Health & social care | 2011 |
| Andar Live Productions Ltd | Information & communication | 2026 |
| Anderson Ames Taping Limited | Construction | 2021 |
| Anderson Gray Associates Limited | Health & social care | 2016 |
| Anderson Leadership Training & Assessment Services Ltd | Education | 2023 |
| Andrew Allan Architecture Ltd | Professional & scientific | 2017 |
| Andrew Cassley Projects 2 Ltd | Professional & scientific | 2025 |
| Andrew D Scott Ltd | Construction | 2019 |
| Andrew Mathie Property Holding Ltd | Real estate | 2019 |
| Andrew Mathie Roofing & Roughcasting Ltd | Administrative & support | 2017 |
| Andrew Surveyancing Limited | Construction | 2025 |
| Andrews Art Ltd | Manufacturing | 2019 |
| Angel Aesthetics by C.E.M Ltd | Other services | 2023 |
| Angels Share Sailing Holidays Ltd | Transport & logistics | 2021 |
| Anlr Properties Ltd | Real estate | 2020 |
| Anna Naughton Ltd | Professional & scientific | 2023 |
| Annya International Limited | Transport & logistics | 2012 |
| Anvil Computer Services Limited | Information & communication | 2002 |
| Apex Accountancy and Business Services Ltd | Professional & scientific | 2023 |
| Apex House Ltd | Wholesale & retail | 2023 |
| Apex Property Management & Investments Ltd | Real estate | 2025 |
| Apex Ropes Ltd | Administrative & support | 2025 |
| Apmc Property Management Limited | Other services | 2020 |
| Apollege Ltd | Professional & scientific | 2021 |
| App Stack Ltd | Information & communication | 2022 |
| Appin Nursery & Creche Limited | Health & social care | 2011 |
| Appletree Bond Limited | Hospitality | 2016 |
| Apux Ltd | Transport & logistics | 2025 |
| Aqualytix Ltd | Information & communication | 2026 |
| Aquarius Contact Centres Limited | Information & communication | 2009 |
| Aquarius Events Ltd | Administrative & support | 2026 |
| AR Commercial Consulting Limited | Information & communication | 2025 |
| ARA Geoservices Ltd | Construction | 2020 |
| Arbtech Limited | Administrative & support | 1991 |
| ARC Developments (Scotland) Ltd | Real estate | 2021 |
| ARC Engineering 2016 Ltd | Manufacturing | 2016 |
| Archway Metals Limited | Administrative & support | 2007 |
| Ardelis Ltd | Professional & scientific | 2011 |
| Ardent Property Solutions Ltd | Construction | 2007 |
| Ardfab Ltd | Professional & scientific | 2026 |
| Ardua Sheq Solutions Ltd | Administrative & support | 2016 |
| Arek Joinery Services Ltd | Construction | 2022 |
| Arjun Ahlawat Limited | Real estate | 2022 |
| Arla Property Group Ltd | Real estate | 2025 |
| Arneil Live Production Ltd | Administrative & support | 2017 |
| Arodie Ltd | Wholesale & retail | 2022 |
| Arrabella Interiors Ltd | Wholesale & retail | 2024 |
| Arrowfin Limited | Information & communication | 2014 |
| Art Interior Service Ltd | Manufacturing | 2025 |
| Art Investment Incorporated Ltd | Wholesale & retail | 2025 |
| Artemis Admin Ltd | Administrative & support | 2025 |
| Artisan Cheesecakes Limited | Manufacturing | 2014 |
| AS Globex Ltd | Wholesale & retail | 2026 |
| ASA Retail Solutions Ltd | Wholesale & retail | 2018 |
| ASC Fencing Limited | Construction | 2018 |
| Ascend Group Holdings Limited | Financial services | 2025 |
| Ascension Property Investments Limited | Construction | 2020 |
| Asdd Consulting Limited | Professional & scientific | 2012 |
| ASH Cabs Ltd | Transport & logistics | 2023 |
| Ashburn Music Limited | Arts & recreation | 2024 |
| Ashley Clarke Signature Salon Limited | Other services | 2018 |
| ASK Dunfermline Property Ltd | Real estate | 2025 |
| ASP Rally Limited | Arts & recreation | 2008 |
| Aspect Scaffolding Hire and Sales Ltd | Construction | 2024 |
| Aspire Vehicle Sales Ltd | Wholesale & retail | 2005 |
| Assaye Holdings Limited | Financial services | 2020 |
| Assaye Technologies Limited | Information & communication | 2020 |
| Astra Cyber Limited | Professional & scientific | 2019 |
| Astrosat Newco Limited | Extraterritorial | 2020 |
| Astute Renewables Ltd | Construction | 2024 |
| AT COR Community Interest Company | Administrative & support | 2009 |
| At-Photo Ltd | Professional & scientific | 2010 |
| ATA Sons Ltd | Health & social care | 2018 |
| Atag Heating Eire Limited | Construction | 2013 |
| Athena Systems Ltd | Mining & quarrying | 2025 |
| ATS Letting Ltd | Real estate | 2017 |
| Attica Greek Ltd | Hospitality | 2022 |